1. Field of the Invention
A method of forming perforating teeth in a perforating blade or rule for use in business form machines and other paper processing machines for applying perforations to business forms or other paper products.
2. Description of the Related Art
Perforating rule and blades are used in business form machines in order to apply perforations to business forms. Generally, perforating rule is made straight while perforating blades are circular, both being made in a variety of sizes. In normal use, the perforating rule and blades are required to be replaced quite often and therefore, they are packaged and purchased in large quantities and are readily disposable after use.
The perforating rule and blades include perforating teeth formed along a sharpened edge. The teeth are specifically structured and designed to form perforations in the business forms by either positioning the forms under the perforating rule where they are stamped or by feeding the forms through the machine so as to pass into contact with a rotating perforating blade which applies the perforations to the forms.
The perforating teeth in the perforating rule and blades in the related art are conventionally formed with punches and dies. This technique has been found to be expensive in producing large quantities because it limits production speed. Additionally, forming the perforating teeth with punches and dies creates burrs and distortion in the rule or blades making them undesirable for use in the business form machines. Specifically, the burrs created from punches and dies results in snagging of extraneous fiber making it difficult to strip the rule and blades from the perforated forms.
Included in the related art are U.S. Pat. Nos. 4,010,666 and 3,973,452 both of which disclose a cold rolled steel perforating blade wherein the blade height to blade thickness ratio is a critical aspect, resulting in proper contact with a mating anvil.
U.S. Pat. No. 3,248,987 discloses a rotary cutter, wherein a blade having no teeth is formed from an unhardened flat ring squeezed between matched dies. Additionally, U.S. Pat. Nos. 3,554,070; 3,147,658; and 2,842,202 disclose a flexible L-shaped perforating blade which is attached to a cylinder with an adhesive. The perforating blades in these patents include a variety of desirable teeth configurations.
Finally, U.S. Pat. No. 4,745,835 discloses a perforating tooth configuration for creating extremely fine perforations wherein wire type electrode discharge machinery or lasers are used for cutting the teeth.
Accordingly, in view of the above patents and the problems associated in the related perforating rule and blade art, there still exists a need for perforating rule and blades which can be produced at a much greater rate of speed at a substantially lower cost wherein the resulting rule and blades include sharp, smooth teeth having smooth tapered sides adapted to be easily stripped from perforated forms. Additionally, there is a need for perforating rule and blades in which the teeth are stronger and adapted to last longer having less tendency to distort during use.